1. Field of the Invention
This invention relates to a foldable shade or blind for use in covering windows of vehicles, and particularly aircraft windows, to prevent penetration of sunlight through the window and to resist the deleterious effects of such sunlight upon the foldable shade.
2. Summary of the Prior Art
Many vehicles, such as aircraft and mobile homes, have windows that are exposed for many hours to direct sunlight. Ordinary shades applied to such windows may cut off the sunlight but, in a short time, the shades assume a wrinkled and faded appearance, which adversely effects the external appearance of the entire vehicle. This is particularly true of aircraft wherein a large number of windows, each having its respective shade, define a substantial portion of the exterior of the aircraft.
A common form of sunshade employed in aircraft utilizes a sheet of woven plastic or textile materials which is horizontally reversely folded to define a plurality of interconnected pleats. The pleats can be compressed into a small space above the window with the faces of adjacent pleats in abutment. To cover all or part of the window, the lower portion of the pleated sheet is pulled downwardly, thus angularly separating the pleats to cover all or part of the window.
While these pleated sheets perform the function of preventing undesired sunlight entering the cabin of the aircraft, the heat generated in each shade by sunlight incident thereon is sufficient to effect a substantial expansion of the textile material. Textile materials do not, however, consistently thermally expand or contract. Thus, as shown in FIG. 1 of the drawings, prior art shades repeatedly exposed to sunlight rapidly assume a wrinkled configuration due to the fact that the textile material expands, but does not consistently contract to its original dimensions when removed from the sunlight.
There is, therefore, a distinct need for a shade for vehicle windows that can be exposed for many hours to direct sunlight without undergoing any permanent change in configuration of the shade.